Converting the gas network to hydrogen

15th August 201612:33 pm15th August 201612:33 pm

Mark Crowther, Technical Director, Kiwa Gastec

Last month we reported on a two year project in Leeds to investigate how hydrogen could be used for domestic and commercial heating in place of natural gas. Mark Crowther, technical director at Kiwa Gastec, makes the case for conversion.

(Credit: Michal Osmenda via CC)

It’s a well known fact that the Climate Change Act commits us to reducing our carbon emissions by 80 per cent of their 1990 levels by 2050. It’s a less well known fact, however, that our heating system accounts for over 30 per cent of our carbon emissions. It follows, therefore, that if we can decarbonise the heat sector, we’ll go a long way towards reaching our overall carbon reduction targets. Sounds simple? Well, it turns out that it could be just that – simple.

We’ve recently played a significant and integral role in the development of a series of reports investigating the feasibility of converting our gas transmission network from natural gas to hydrogen.

Working alongside the likes of Northern Gas Networks, KPMG and the Department of Energy and Climate Change as it was, our team at Kiwa Gastec assessed the benefits of a change to hydrogen over other low carbon forms of energy; the technical feasibility of using existing infrastructure to store and transport hydrogen; the safety implications of using the gas in a domestic setting; the practicalities of establishing a supply chain for the appliances that would ultimately use it; and investigating a viable location for piloting a physical conversion. In other words, we’ve looked at each piece of the jigsaw puzzle and have created a whole picture view of what conversion would entail.

And the conclusion of all this work? Having been involved in all aspects of the research, I can say with certainty that conversion of the heat sector to hydrogen is technically feasible.

Of course, decarbonisation of the gas network will be challenging, but thanks to our work on the H21 Leeds City Gate project, which has assessed the feasibility of replacing natural gas with hydrogen in the city, we have shown that these challenges can be overcome.

Assessing the infrastructure needed to facilitate the conversion was the first step and a relatively easy one to address. We are part way through an ongoing network upgrade, due to be completed by 2032, through which the country’s low and medium pressure distribution network is being replaced with polyethylene pipes – which, conveniently, are suitable for transporting hydrogen. Utilising the existing gas network will significantly reduce the scale and complexity of the decarbonisation challenge.

Establishing the volume of hydrogen needed and ensuring security of supply was next, and again, the solution was clear. The use of Steam Methane Reformers (SMRs) is the most viable way, both technically and economically, of supplying the large amounts of the gas required. With an existing SMR plant at Teeside, it would be feasible to scale this up to the four SMRs needed to meet the demand of a city the size of Leeds – the likely location for a pilot conversion.

Leeds is the most likely location for a pilot conversion scheme

Importantly, the North East also offers a viable solution to the issue of carbon capture and storage. In the USA, SMRs are already being used alongside existing CCS technology to capture the carbon separated during the creation of hydrogen. Mirroring this process at a Teeside plant, the captured carbon could be transported via a pipeline to be stored in the gas strata under the North Sea. The Humber would also provide a suitable location for storage of hydrogen during the summer months, to help manage the variation of demand between the seasons, in the form of the underground salt caverns that exist in the area – a proven mechanism for gas storage.

A further challenge is how to carry out a conversion with minimal impact on end users. Again using Leeds as an example, we have established that it would be possible to convert approximately a third of the city each summer (when gas demand is at its lowest) for three years, causing just a few days’ disruption to householders. So another tick in the box.

The final challenge is making this a reality.

I can say with certainty that there is the will within the industry to make it happen. I know first-hand from the conversations I’ve been having that people are paying real attention to the evidence base we’ve established and they’re excited about it.

The key, therefore, is creating the certainty and incentive that is needed to get the industry to commit to the financial investment needed – and that can really only be achieved by a political decision. Government needs to demonstrate a serious commitment to this on a national scale.

If that commitment is made, and assuming that industry and government work together to make this happen, I firmly believe that hydrogen offers a high level of decarbonisation at a modest cost using a proven supply chain. In other words, it has a tremendous amount going for it.

You can reduce heating costs by up to 80% if you insulate your home properly. THAT is also more interesting for the user as he won’t replace costs for conventional gas with costs for hydrogen. And possibly the insulation is cheaper than the conversion of current pipes and equipment to hydrogen transport.

Overhauling your walls, roofs and floors to insulate them will also help you to discover mould. Mould being not very beneficial for your respiratory system (asthma, bronchitis, sinusitis).

Insulating your house therefore could even be beneficial for the NHS and productivity.

You’re right, Ralf. One also wonders if mould is a major contributor to lung health problems – and not the current, rather questionable cause – diesel-powered transport. The environmental groups were very slow to recognise that indoor pollution can be 10x that of outdoors, and most medical research groups have rarely undertaken proper studies of indoor pollution, again preferring to blame vehicle traffic as the cause.

I’m afraid it’s both. Research being done all over the world, in different languages. The effects of fine dust (Feinstaub) from diesel and fossil fuel is researched heavily in Germany for example.

Mould on the other hand is fungus. And when you talk to a doctor in regard to fungus, they all tell you, you can’t have that. Current state of knowledge is you only get fungus related diseases if you are sick, very sick, like AIDS or cancer. Somehow in modern medicine health is binary. Either you are sick, or you are healthy. You can’t possibly be a bit sick…

Surely the best thing to do with hydrogen is to put it into fuel cells ? Whether these are powering cars, fridges or heat pumps, generating electricity with a fuel cell is more efficient than simply burning hydrogen. Carnot (=perfect) heat engine efficiency is limited to 50% (1-Tc/Th) where Tc and Th are the absolute hot and cold reservoir temps in K. Fuel cells are not heat engines and can go much higher – 85%.
Once you have electricity, you can do heating with heat pumps – which are governed by good old Carnot again – but this time they don’t reduce it, they multiply your energy. You can get 3 to 5x as much heat out as you electricity in.

Home insulation is not the panacea that it seems, though obviously has an impact on consumption. But the point is that of facilitating a change to hydrogen as a fuel on this scale. It looks promising. From experience not everywhere can be as well insulated, and insulation brings its own problems anyway, such as fresh air circulation. If the conversion was done in the same way as we did for natural gas (from recollection nil cost to users?) then there would be no significant opposition. In safety terms there isn’t much to distinguish between a gas explosion or fire and a hydrogen one so this issue should be be seriously considered. If it only requires re-jetting then it should be easy. Good idea so get on with it!

I can remember when they converted everyone from coal gas to natural gas in the early 1970’s.

They just swapped all the jets on gas appliances, so it’s feasible, but that’s just the one off cost.

The real question is how much more will hydrogen cost the consumer and will there be any cost to the tax payer? (Like there is with solar energy. The taxpayer is forced to pay more than 30 pence per KWH to the owners of solar panels, then sell it to the grid a less than a quarter of that price.)

Ian – the ‘tax payer’ doesn’t fund those of us who have invested in solar panels, the subsidy comes from a levy on electricity bills. The actual rates paid vary widely depending on the size and date of installation. Many installations get less than 30p per kWh. New domestic installations are now subsidised by less than the retail price of electricity.

Robert, all solar power and wind is massively subsidised by the populace, even if it also manages to catch some of the legion of non-tax-payers. no one would invest in either without the funded returns that are guaranteed.

There is just so much here that doesn’t appear to have been considered.
I can also remember that change from coal gas to methane and the 30 gas fitters it took to fix our cooker. The increased heat output compared to coal gas required more than just re-jetting ; cooker grids also had to be raised to prevent local overheating.
How much extra money and energy will it cost to ‘convert ‘ methane to hydrogen ; that is in total energy balance including the energy needed to build all the required 300 SMR’s for the UK, assuming 80% on mains hydrogen and 196k people per SMR ( on the Leeds scale).
What will be added to make it smell so that it can be detected? As we know hydrogen doesn’t smell and its fire can be invisible. The molecules are also much smaller than methane and thus permeation is also an issue, particularly when considering storage.
I presume that there is a mis-print in the article ; assuming the system uses the partial oxidation method it should read ‘carbon monoxide’ not ‘carbon’ being pumped to the North Sea gas pockets.

It’s a good point about fuel cells but they would require considerable changes in the heating equipment so would be suitable mainly for (any?) new build housing and office blocks. Likewise many people have already insulated their homes with 12″ loft, cavity, dual glazing etc, so there is only a reducing return there.

I don’t know about the cost of hydrogen compared to natural gas but at the moment I suspect it is rather more expensive. This is the key issue – as always. If we can have a technology that delivers (preferably solar or renewable energy powered) hydrogen at a comparable cost then it seems to be fairly straight forwards to convert the gas network. My concern is that generating H2 as a by product of CCS assumes we would continue to be using fossil fuel in electricity generation.

The next target must be transport, including aviation, where the much larger stored energy in H2 will make a considerable impact and here hydrogen fuel stations, fuel cells and electric drive, particularly in road vehicles, must come into its own.

Isn’t hydrogen versatile? And , of course, we are surrounded by hydrogen locked up with oxygen in the form of water, being an island. If we moved to build an industry to extract hydrogen, using solar or wind to provide the electricity for electrolysis I expect we could be energy independent in 5 years.

Hydrogen has serious safety disadvantages: 1) it has a negative Joule-Thompson coefficient, so if a leak occurs and it expands, it can set itself on fire. I fought a lot of those fires in a refinery I used to work at. 2) The fires, when they happen, are almost invisible, so it’s possible to walk into one and be seriously hurt. 3) the molecules are so small and it is so active it can pass through solid steel, and when it finds a flaw, it will accumulate there and make a bubble, compromising the strength of the steel. For this reason, I would be surprised if it can be contained in a salt dome. It doesn’t look like the proponents have done their homework.

Mark Crowther is selling his “product” hard, but the only way that this could ever be developed is through massive funding. As Kirby Mohr says, hydrogen has many very difficult and dangerous properties that make safe handling very difficult. Neil Downey is also correct that hydrogen is the perfect fuel for power generation at very high efficiency, (if it could ever be made economically of course).

If wood is considered green fuel, why not go back to home heating using this…… in my opinion this is more snake-oil, but it is still preferable to making hydrogen then wasting it.

Wood isn’t climate-friendly. Heating a home with wood causes more global warming (in the critical period between now and when we expect to exceed 1.5 degrees of warming) than heating a dozen similar houses with an efficient electric heat pump – woodsmoke .3sc .net/ghg (remove spaces).
As Neil A Downie said: “you can do heating with heat pumps – which are governed by good old Carnot again – but this time they don’t reduce it, they multiply your energy. You can get 3 to 5x as much heat out as you electricity in.” Some of the more efficient models can even give you 6 times as much heat!

How could something NOT be afoot in Teeside? The Engineer article of 12 August 2016 by Jason Ford [https://www.theengineer.co.uk/finance-agreement-triggers-worlds-largest-biomass-power-project/?cmpid=tenews_2539070] discusses secured finance of £650m for a 299MWe combined heat and power (CHP) plant powered by wood pellets at least partly from the ‘boon’ of feed stock brought about from the northern hemisphere mass tree die-off (but for now let’s delay facing controversy about that climate ‘canary -in-the-coal mine’). As hydraulic fracturing is practically a ‘done deal’ in the UK despite the UK’s unprecedented democratic and intellectual public debate compared to the disasters we’ve had foisted upon ourselves on this side of the pond… The point here is that if the SMR plant/hydrogen grid initiative never gains ground, Teeside will have plenty of Methane from fracking and, whilst the CHP plant is apparently of mixed-fuel boiler design, there still could be enough biomass to fuel a methane digesting plant – to hedge the bet, so to speak. Regardless, a nearly sure bet is we’ll soon hear of a CCS project being financed for a pipeline to store carbon in the gas strata under the North Sea; or at worse an ‘externality’ , Teeside’s political problem, if the fracking mob takes cues from how the nuclear industry has historically handled the ‘back-end’ of waste management/disposal (costs too much to even think about)…

What a waste- Still using fossil fuels, converting which reduces efficiency and then there’s the cost. After reading the previous comments I would add – you can’t create energy and if you convert it you will end up with by-products, which in this case seem to be the nasties you want to eliminate, which you need to deal with and hiding them in the ground and trying to ignore them is just stupidity.

The most efficient way to produce power and use it is to have no gap of transport.This means producing the majority of power used on site, solar panels with storage units would be clean and easy to upgrade- but vested interest will keep their end up even though its not the greenest way to the future.

Given the safety aspects, well highlighted by Kirby Mohr et al. and the well-know airship disasters that the public associate with Hydrogen, I think you’re going to have a hard time selling this idea to the general public!

Hello all. I work at Kiwa Gastec and I’m here to respond to the comments and questions. As with any article there is limited space as to what level of detail can be included, so it’s hard to summarise over 300 pages for posting online.

The first point raised was that of insulation. This is one of the first areas which was examined for comparison purposes. I’m not sure where the 80% reduction quoted comes from. DECC conducted an analysis of the National Energy Efficiency data in 2015, and found that it is possible to reduce heating costs to 80% (i.e. a 20% reduction) through a combination of insulation and replacing a boiler with a more efficient model.

Insulation improvements in practice don’t always work out as expected. Installation on the least efficient houses, or those of people living in fuel poverty, results in increasing the temperature inside the house to sensibly increase comfort before it results in efficiency improvements, so the projected kWh per year savings and associated carbon footprint reduction do not necessarily materialise. External solid wall insulation (which is the most efficient measure) costs more than the H21 Leeds City Gate project would cost distributed across connected properties.

Fuel cell efficiencies are around 40-60% on an electricity generation basis, with heat cogeneration needed to get it up to 85% overall. For applications where the heat would be wasted, the lower efficiency is what would be realised. But that’s not the case here! Amongst the proposed work packages of the study is development of new appliances, including cooking and heating appliances using fuel cells or catalytic combustion. Some of these are available now, and it becomes an integration and commercialisation challenge rather than a matter of fundamental research. For these domestic applications, the efficiency of fuel cells is comparable to that of modern heating equipment.

Changing the fuel to a gas fired appliance, and converting or replacing the appliance, is much less complex and costly than retrofitting heat pumps into the bulk of the existing housing stock. The Building Regulations already require plans for new build houses to consider heat pumps, district heating, and other options before using ‘traditional’ gas heating. But this isn’t a project for building a new town or city using new technologies – as interesting and useful as that would be – it is intended as a practical option that could be done at least disruption to an existing population.

The cost of the project is an important part of the work, and must meet with OFGEM approval as transmission costs are regulated. Part of the financial model is that as the iron main replacement programme concludes, the portion of the bill that is currently used for that infrastructure work could instead be allocated to this project. With the 45 year regulatory depreciation model, this allows the cost to be spread. As this project is intended to go a long way to achieving the carbon dioxide emissions targets for the country as a whole, the proposal is that the cost should be met from part of the distribution charges paid by all gas users countrywide. The project should be cost neutral to consumers who are moved onto hydrogen compared to those remaining on natural gas, other than for those who have old, inefficient appliances replaced with new ones and use less energy as a result.

It’s worth stressing that the cost of the work does not go into the gas companies’ coffers as profit. It is expenditure aimed at meeting legal targets under the Climate Change Act. And where parts of the cost are spent on labour (such as the gas fitters performing work) there will be a flow back to the Treasury in terms of income tax.

The conversion of appliances to run on hydrogen is critical to safe and effective operation, and requires working out what can be done with the existing appliance stock. The physical properties of hydrogen differ from natural gas such that the flame will be shorter, but for a given supply pressure from the meter will give a very similar heat output, which differs from the experience of the conversion from coal gas to natural gas. The conversion process will be similar but have different challenges to that of the 1960s and 70s. Various research projects are currently under development to support this.

As for gas storage, it would be carbon dioxide that would be stored under the north sea as part of the CCS strand of work. It’s just referred to as carbon as standard for brevity. To reassure Kirby Mohr, hydrogen is already stored in salt caverns under Teesside. It’s a proven storage method.

The self heating of hydrogen leaks is a well known phenomenon, and was investigated in a report commissioned by the HSE in 2008. A hydrogen leak to atmosphere from 500 bar (much higher than would be used here) will heat by between 9 and 18°C, which would not be enough to reach the 585°C needed for hydrogen autoignition. Instead, there must still be another ignition source (electrostatics for example) which does not need to have much energy for hydrogen. The low density of hydrogen is a helpful safety feature in practice. If there is a leak, it will be carried vertically away much more quickly than natural gas will. An experimental study conducted by Kiwa for DECC called HyHouse showed that the risks from a hydrogen leak within a house are similar to those currently borne from natural gas.

The obvious necessity is stopping hydrogen from leaking in the first place. The Gas Distribution Networks are currently replacing their iron mains with polyethylene, which does not suffer from the same leaks of hydrogen as the iron mains (some of which are well over a century old) do. It’s also worth remembering that coal gas was also around 50% hydrogen, and the biggest hazard was carbon monoxide poisoning from leaks in houses rather than fires or explosions from the hydrogen component. For transmitting hydrogen at pressure from its point of synthesis to where it is let down to distribution pressure, there are specific grades of steel alloys which would be used which don’t suffer from the same hydrogen embrittlement issues as the current (hydrogen incompatible) natural gas transmission lines do.

An odorising agent will need to be applied to the hydrogen before it can be distributed to mains. This still needs to be chosen. The current agent used for natural gas in the UK would poison fuel cells so is not ideal. There are many chemicals with distinctive smell, the challenge is choosing one which is noticeable enough and will not cause problems for end use appliances.

The Hindenburg was indeed a striking disaster, and almost 80 years later it still gets mentioned in relation to any hydrogen project. It’s often forgotten that most of the passengers and crew survived. But if we were to assume that safety precautions have remained unchanged we would be doing a disservice to engineers and make no progress. Safety of hydrogen is paramount now to a degree that was not the case then. Flammable gas detection, rules regarding escape routes, high flow shut off valves amongst other risk reduction measures all act to improve safety. The fundamental nature of a hydrogen flame – whilst without attempting to understate the danger to anyone or anything within the flame – is less destructive to the surroundings than less buoyant gases are. Hydrogen is produced and used on an enormous scale in industry throughout the world, without major safety concerns.

This project is not a panacea. It is intended to be part of a range of measures. Generation of hydrogen through reforming natural gas and capturing the carbon dioxide may perhaps be described as olive in colour – it’s not quite green but it’s not as brown as the current heating infrastructure either. Hydrogen generation via renewable electricity sources and grid connected storage to account for the intraday and interseasonal variations in supply and demand is the long term approach that this project aims to kickstart. The smoothing of peaks and troughs is important. The energy used for heating and cooking significantly outstrips the energy demand for lighting, electronics etc in a house, and the difference between demand in the summer and demand in the winter is very large. Gas suppliers have to be able to deliver the projected gas demand for the worst day in twenty years. Any decarbonising strategy must account for this variation, and the ability to compress and store hydrogen gas does not present insurmountable problems.

Good detailed response to all of the queries raised Paul, I’m sure that we are all grateful for your effort. I’m still not convinced that this is an economic or thermally effective solution as hydrogen is just too good to just burn in an open flame, but will read what you have said carefully.

Excellent response from Mr Mc Laughlin. I have only a few small comments ref the comparison of domestic gas boilers.
1) I have not found any definitive ref to what is meant by ‘old’ and what is meant by ‘modern’ therefore the efficiency figures often quoted have no real meaning.
2) Carbon footprint of a ‘modern’ boiler does not cover cradle to grave. I have over many years monitored older and newer heating plant (domestic) and found that the older require a lot less maintenance and have less throw away parts.
Hydrogen offers a long awaited base for a common fuel policy. Wind and PV could contribute to this H2 base.
SMR’s in my world are Small Modular Reactors and these could also be part of the H2 base putting H2 into the hydrogen gas network when electricity demand is lower in the early hours of the day.
Wishing you good progress with hydrogen

Ian Downie
I can remember when they converted everyone from coal gas to natural gas in the early 1970’s.
They just swapped all the jets on gas appliances, so it’s feasible, but that’s just the one off cost.
The real question is how much more will hydrogen cost the consumer and will there be any cost to the tax payer? (Like there is with solar energy. The taxpayer is forced to pay more than 30 pence per KWH to the owners of solar panels, then sell it to the grid a less than a quarter of that price.)

Not the taxpayer ie through the governments collected funds, no its the other energy users who are “forced” to subsidise these lead in tariffs. If its not economic, do not force others to underwrite it.

Electrical equipment in a flameproof enclosure can be used in a building that can contain methane. There did not used to be an equivalent for a building that can contain hydrogen. I recall one such building was erected with a light weight roof in case of explosion. Perhaps I am out of date.

fellow bloggers might recall my comment(s) about only ‘conditioning’ (and lighting for that matter) those parts of a massive textile mill where the process actually required it. A substantial overall energy saving resulted. Are we seeking to warm/heat all parts of our homes (and offices for that matter) to the same ‘level’ when only the parts where the family/staff) are at the time actually need such. I have not put that particularly elegantly, but perhaps some ‘lateral’ thinking across the entire ‘domestic’ heating scenario might be of merit. I have always believed that there is enough of everything we need -IF WE DID NOT ALL BELIEVE WE NEED IT AT THE SAME TIME. [Our Victorial ancestors -there they are again!- seemed to create acceptable ‘conditions’ for a much greater percentage of the population than formerly, by valuable thought and careful planning. Thankfully we do not need to remove 10,000 tons of horse-excrement per day from our towns and cities: so it should be much easier for us?
Has that set some lateral thinkers a’thinking? I hope so.